The idle on a 1.9td is adjusted using the long screw that is almost vertical and sets between the IP and the head. It is very long and thin with a spring around it. If that doesn't get you enough, you can adjust the residual fuel which is a horizontal screwthat lays horizontal along the IP body, very close to the idle screw. The residual fuel adjustment has a 10mm locknut on it.
What ever you do, don't use the smoke screw to adjust the idle. The smoke screw is close to the residual fuel screw but has a 13mm locknut and a head that takes a 6mm wrench or a screwdriver. HTH.